How Much Does Window Replacement Cost? UK Prices for 2026

Double glazing quotes are the last great British haggling ritual. Two firms measure the same eight openings and come back at £4,200 and £11,000, and neither explains the gap. A window is three purchases bundled into one number — the frame, the sealed unit, and the labour to get it plumb, sealed and signed off — and most of the difference hides in the third.

Below: real per-window costs, the regulations that add to them, and three worked jobs with the maths shown.

Supplied and fitted, a replacement window lands between £400 and £2,500. The median UK job — a standard uPVC casement in a three-bed semi — sits at £600 to £750 including VAT, fitting, external sealing and the compliance certificate.

London and the South East run 15 to 25 per cent above these figures, mostly on labour; the North East, Yorkshire, much of Scotland and Northern Ireland run 10 to 15 per cent below. First, though, work through the signs your windows need replacing — plenty of cold rooms are a gasket problem, not a frame problem.

• •uPVC casement, standard 1200 x 1200mm: £480–£800 fitted
• •uPVC vertical slider (sash-look): £850–£1,400 fitted
• •Slim-frame aluminium casement: £900–£1,600 fitted
• •Engineered softwood timber casement: £900–£1,500 fitted
• •Hardwood or Accoya box sash, made to match: £1,600–£3,200 fitted
• •Bay window, three to five lights: £1,500–£3,800 fitted
• •Whole house, 8–10 uPVC windows: £4,500–£8,500
• •Whole house, 8–10 timber box sashes: £13,000–£25,000

On uPVC the split is roughly 70 per cent materials to 30 per cent labour; on timber it moves to 55/45, because a joiner spends far longer easing, packing and painting. A two-fitter team charges £320 to £450 a day and clears four to six windows — hence per-window labour of £70 to £110.

Argon-filled double glazing with a soft-coat low-E pane is standard; triple adds 15 to 25 per cent and only repays in exposed or noisy locations, as our double versus triple glazing comparison sets out.

• •Sealed unit, 4-16-4 argon, soft-coat low-E: £55–£110 per m²
• •Triple-glazed unit: £95–£170 per m²
• •Frame profile, fabricated to size: uPVC £150–£280 per opening, aluminium £400–£850
• •Factory-fitted trickle vent: £18–£35 per window
• •Toughened or laminated safety glass: £35–£90 per pane
• •Scaffold tower hire: £90–£160 per week; full scaffold to a two-storey semi: £700–£1,400
• •Waste removal: £180–£350, or £25–£40 per window
• •Making good reveals and sills: £40–£90 per window
• •Rotten sub-sill or lintel repair: £120–£400 per opening

Replacement windows are controlled work under the Building Regulations, which is where cheap quotes get exposed. Most installers self-certify through FENSA or CERTASS — the certificate posted to you weeks later, costing them £20 to £30. If your fitter is not on a competent person scheme, you need a building control application to the council instead: £200 to £400, paid by you.

Scotland differs, needing a building warrant or an approved certifier of construction; Northern Ireland takes a building control notice. And windows do not qualify for zero-rate VAT on energy-saving materials, so 20 per cent applies whatever the salesperson implies.

• •Part L (England): 1.4 W/m²K or WER band B. Wales sets 1.6 W/m²K or band C. 'A-rated equivalent' with no number is marketing, not compliance.
• •Part F: trickle vents are required on almost every replacement in England and Wales since June 2022, even where the old window had none. A quote without them is a variation waiting to happen.
• •Part K: safety glazing below 800mm in a window, or 1500mm in a door and its side panels. Budget £35–£90 per pane.
• •Part B: habitable rooms above ground floor need an escape window of at least 0.33m² clear opening, 450mm each way. A small top-hung replacement quietly breaks this.
• •Conservation areas, Article 4 directions and listed buildings: front elevations need consent and must match the original material and sightline. uPVC is routinely refused.
• •Landlords: MEES requires EPC band E, and windows alone rarely move a band.

Access and timing beat haggling. A first-floor bay over a conservatory roof adds £400 to £900 in scaffolding, and a firm with a January gap will discount 8 to 12 per cent it would never offer in June.

A rattling 15-year-old unit with failed gaskets is a £30 fix, not a £700 one — start with curing a draughty window and draught-proofing the house. If the frames are original timber, restoring rather than replacing is often cheaper and better.

• •Frame colour: anthracite grey foil adds £40–£90 per window; dual colour more
• •Opening lights: a fixed pane is £80–£150 cheaper than an opener of the same size
• •Hardware: Secured by Design cylinders and multipoint locking add £25–£60, and satisfy most insurers
• •Order size: ten windows in one visit beats two visits of five by around 15 per cent

Real quotes, real houses, all figures including VAT. The second job shows what hides behind old frames; the third, what planning constraints cost.

If a back door is going in too, bundle it into the same visit — our door installation cost guide assumes a standalone job, and combining usually saves £150 to £250.

• •1960s three-bed semi, Derby. Eight white uPVC casements, trickle vents, tower access upstairs. Materials £3,150, labour £1,050, waste £220, making good £480. Total £4,900.
• •1930s semi, Guildford. Nine anthracite grey uPVC windows plus a composite back door, full scaffold to the rear, two rotten sub-sills found on the day. Windows £5,850, door £1,250, scaffold £950, sills £460. Total £8,510.
• •Victorian mid-terrace, Bristol conservation area. Four front box sashes remade in Accoya to match, three rear uPVC sliders, planning conditions on glazing bar widths. Front £9,600, rear £3,200, planning £258, making good £520. Total £13,578.

The most useful question is the simplest: what is the price per window, excluding VAT? Firms that quote only a whole-house figure, valid today only, are hiding a unit price that will not survive comparison. Get three quotes against an identical specification, then read them the way we set out in comparing contractor estimates.

• •Check the FENSA or CERTASS number on the public register yourself, not in the salesperson's folder
• •Insist the U-value or WER band is printed on the quote, per window
• •Get trickle vents, safety glazing and any escape window specified in writing, opening by opening
• •Establish who makes good the plaster, who takes the old frames away, and whether external silicone is included
• •Treat a deposit above 25 per cent as unusual; made-to-measure goods lose the 14-day cancellation right once manufacture starts
• •Agree an hourly rate for hidden rot before day one

Figures come from installer quotes collected across England, Scotland and Wales in the first quarter of 2026, cross-checked against trade fabricator pricing and hire rates. Unless stated, prices include 20 per cent VAT and assume like-for-like replacement into a sound opening.

Treat every range as plus or minus 20 per cent on your postcode, access and the state of what sits behind the frame. We revisit annually: profile and glass prices are the volatile part.